A emergency transponder signal led emergency personnel to search the area around Three Rivers Airport Sunday morning.

About 9:30 a.m., the Three Rivers Fire Department and Fabius-Park Fire Department were dispatched to the airport after an emergency transponder signal was picked up by another plane and reported to the Kalamazoo Control Tower.

St. Joseph County 911 Center received two cell-phone 911 hang up calls just prior to the transponder report, which added to the concern that a plane and or a pilot was calling for help.

With the coordinated efforts of 911 Central Dispatch, the Kalamazoo Control Tower, and Airport Manager Mark Glessner, the transponder signal was tracked down to a plane inside a hangar at the Three River airport.

The plane was recently brought in to the hangar for maintenance.

The signal stopped when the transponder unit was removed from the plane by technicians from Conrad Aero.